1. Field of the Invention
The present invention relates to magnetic data recording, and in particular to devices and methods for equipping payments cards with magnetic stripes that can autonomously reprogram some of the magnetic data bits recorded.
2. Description of Related Art
Magnetic information storage medias need to retain their data despite thermal fluctuations caused by the superparamagnetic limit. If the thermal energy is too high, the magnetic data stored will be lost. The energy required to reverse the magnetization of a storage medium is proportional to the size of the magnetic field and the magnetic coercivity of the material of the medium. A higher coercivity medium is inherently more stable thermally. Stability is proportional to the product of bit, or magnetic grain volume, times the uniaxial anisotropy constant Ku, which is higher for materials with higher magnetic coercivity.